Drill chucks are conventionally operated by a chuck key to provide tightening and loosening of jaws of the chuck about an associated drill, blade bit, or any other type of tool that is held by the chuck during use. Conventional chuck keys include a shaft having a gear at one end and a handle that projects in opposite directions from the shaft at its other end. Adjacent its gear, the shaft includes an extreme end portion that is received within a lateral hole in the chuck during use such that the key gear meshes with a ring gear on the chuck to effect jaw movement upon rotation of the key about its shaft. Conventional chuck key handles are in the form of a round rod that extends through a hole in the associated shaft end in order to permit application of torque to the chuck key during tightening and loosening of the chuck.
U.S. Pat. No. 1,647,936 as well as numerous other prior art references disclose the type of chuck key described above.
A greater amount of torque can be easily applied to a chuck key with the type of handle construction disclosed by U.S. Pat. Nos. 2,552,694 and 2,592,094. This handle construction includes a thumb end that is flattened in order to permit the manual application of a greater extent of torque during tightening and loosening of a chuck. Also, another type of handle construction for a chuck key as disclosed by U.S. Pat. No. 4,032,160 includes flattened portions at both of its end in order to permit both the thumb and one finger to engage flat surfaces during the manual application of torque to effect chuck tightening or loosening.
A two-piece chuck key construction is disclosed by U.S. Pat. No. 4,111,079 and includes a geared headed part as well as a handle part that are molded, die cast, or forged. The headed part includes a stem portion that is received within a central opening in the handle part during assembly. The handle part of this chuck key has a somewhat flat construction such that the application of torque thereto would be more easily manually accomplished than with the conventional round rod type of handle construction.
My prior U.S. Pat. No. 4,123,195 discloses a chuck key holder for holding a chuck key in spanning engagement with a chuck during the application of torque upon tightening or loosening the chuck. With this type of chuck key holder, it is possible to apply a greater extent of torque during the tightening and loosening. However, the extent of torque that can be applied during tightening or loosening of the chuck is limited by the force that can be manually applied to the chuck key handle. After tightening and loosening of the chuck key with one hand, release of the holder by the other hand provides automatic ejection of the chuck key from the chuck such that inadvertent rotational operation of the chuck cannot take place with the key still engaged.